Background/Purpose:

Data on longer term efficacy and tolerance of biologic therapies in psoriatic arthritis (PsA) are emerging.  Persistence with the first TNF inhibitor (TNFi) at one year is estimated at 70-87%. Data on the benefit of switching between TNFi are limited but persistence with a second agent at one year is reported as 74-81%. We aimed to investigate the treatment response, drug survival and outcome with the first and subsequent biologic agents in patients with PsA.

Methods:

Data were collected from a prospective single-centre cohort of PsA patients who started a biologic agent between 1^stJan 2003 – 1st Sept 2010.

Results:

Seventy-one patients started a biologic agent of whom 96% had polyarticular disease. The median follow-up was 36 months, median age at start of biologic 47y and median disease duration 10y. The most frequently prescribed first biologic agent was etanercept (58%) followed by adalimumab (35%) and infliximab (7%). 

Thirty-six percent started a biologic agent as monotherapy, 49% started in combination with one DMARD and 13% with two DMARDs. Ninety-six percent fulfilled the Psoriatic Arthritis Response Criteria (PsARC) where completed.

Persistence with the first biologic was 92% at 6 months, 87% at 12 months, 74% at 24 months and 70% at 36 months. Six patients (8.4%) stopped due to secondary inefficacy (after 12 weeks) and 16 (23%) stopped due to adverse event.

Nineteen patients switched to a second biologic agent (6 due to secondary inefficiency and 13 due to an adverse event). Persistence was 67% at 6 months and 53% at 12 months. One patient stopped due to primary inefficacy, 2 due to secondary inefficacy and 7 had an adverse event.  Of the 6 patients who had switched to a second agent because of secondary inefficacy, one continued on the second agent, one switched again because of primary inefficacy, 2 switched again because of secondary inefficacy and 2 switched again because of an adverse event.  Of the 13 patients who switched to a second agent because of an adverse event, 8 continued on the second agent, one stopped biologic therapy and 3 switched again because of an adverse event.  One patient was pending switch to a third biologic at the time of analysis. 

Eight patients switched to a third biologic. Six continued on the third agent (median follow up after switching 26 months).  Two switched to a 4^th agent (ustekinumab) because of secondary inefficacy and remained on the 4^thagent at 4 and 11 months follow up respectively.   

Median percentage improvements with the first biologic at 12 and 24 months respectively were 79% and 100% in swollen joint count, 77% and 83% in tender joint count, 50% and 56% in Health Assessment Questionnaire, 67% and 61% in Psoriasis Area and Severity Index, 89% and 100% in Dermatology Life Quality Index and 100% and 100% in the Bath Nail Score. 

Conclusion:

Persistence with the first biologic agent in this cohort was 87% at 12 months, 74% at 24 months and 70% at 36 months. The response to the first biologic agent was sustained at 24 months across joint, skin, nail and quality of life measures. Persistence with the second biologic agent was 53% at 12 months. Patients who switched to a second biologic agent because of adverse event were more likely to continue with the second agent than those who switched because of secondary inefficacy. 

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/psoriatic-arthritis-and-biologic-therapy-treatment-response-drug-survival-and-outcome-after-switching/